Journal of Heredity 16(2): 33-46 (1925)
Tracing the Origin of Civilization Through the Domesticated Plants
U. S. Department of Agriculture

The ancient Peruvians carried the art of agriculture to the highest, most specialized development that has been attained in any part of the world. Their system of agriculture included not only the use of fertilizers to enrich the soil and irrigation through long artificial channels, but also the lands that were cultivated were largely of artificial construction. The photograph shows a stretch of artificial land in the Valley of the Urubamba river near Pisac, a few miles below Cuzco. At this point the bed of the river was straightened and walled and the reclaimed area terraced and covered with artificial soil. The fields that appear as a general level are formed of broad terraces, with narrower terraces on the lower slopes of the mountain and smaller irregular terraces in the coves above.

CIVILIZATION rests upon agriculture, and agriculture upon the domestication of plants. The most primitive savages wander in search of food, like predatory animals. To maintain a food supply, storage or cultivation is required, or a combination of the two. With a settled existence achieved, the experience of successive generations begins to accumulate, and an advance toward civilization becomes possible. "That there may be permanence and progress in society the individuals who compose it must be located." This necessity of location was supplied by a threefold domestication, of plants, animals and fire. For primitive man, the fire also was a living creature which had to be tended and fed, in order to keep it alive. Domestication was the great achievement which enabled primitive man to attain what may be considered as a human existence.

With every extension of agriculture into different regions, primitive man was under the necessity of domesticating more plants or animals. Eventually civilization became possible over a large part of the earth's surface, when enough plants and animals had been domesticated to meet the requirements of the different conditions. Such domestications must have been accomplished at a very primitive stage, while recourse was still had to wild food products in times of scarcity, so that there were practical tests of the edible qualities of many species. Thus it appears that all of the important food plants were domesticated before the historical period, or several thousand years ago. On account of the great antiquity, it is not easy to determine whether different systems of agriculture arose independently or an extension of agricultural habits took place, from one original center. Only a few writers have considered the possibility of reconstructing the early stages of human progress and eventually locating the original seats of civilization by tracing the biological relations of the domesticated species.

Tracing the origin and places of domestication of cultivated plants is of present-day agricultural importance as well as of historical or ethnological interest. Knowledge of the wild prototypes of cultivated plants is essential to a full understanding of problems of adaptation and breeding, and for developing more vigorous and resistant varieties to replace any that become weak or diseased. The most specialized adaptations to particular conditions of growth are likely to be found in the regions where the plants have been cultivated for the longest periods. Also the greatest accumulations of experience in cultivating, propagating and using the various domesticated species are likely to be found in their native regions.

If cultivation arose independently in different parts of the world, as many writers have assumed, the several points of origin would represent as many centers of domestication of plants, where different systems of agriculture had separate beginnings. In view of the very slow adoption of civilization and of agricultural improvements, even in the more advanced countries, and the failure of so many peoples to maintain the civilizations that are known to have existed formerly in many regions, the theory of multiple origins and independent developments of primitive civilizations is less easily credited. To locate the primary centers of domestication as definitely as possible would appear to be the first step in a biological investigation of the conditions and stages of human progress in prehistoric times.

Figure 1
Figure 2
A perfection-point of prehistoric agriculture. Five of the megalithic terraces are shown, built of hard, white granite, the stones of irregular form but fitted together with an incredible nicety, showing that a high state of artistic ability as well as of social organization existed at a remote period. Enormous blocks of red granite that must have been transported for several miles are shown above the terraces. For other photographs see "Staircase Farms of the Ancients, National Geographic Magazine, May, 1916. A valley in the high table land near Sicuani at an altitude of about 12,000 feet, where the valleys are not so deeply eroded and there is land that can be cultivated without terracing.

In the present state of botanical science there can be no question that each of the cultivated plants had an original status as a wild species, and was adopted by primitive man at some time and place, which it is our problem to locate as definitely as possible. The domestication of a new food plant was a step of the utmost importance in the subsequent history of mankind, not only in the country of origin but even in remote regions to which many plants have been carried. No other physical cause of the modern industrial and political ascendency of northern Europe is so important as the introduction of the potato from the tablelands of Peru, which has enormously increased the productive possibilities of Germany and other northern countries, and thus made possible the recent "World War." Although the extensive cultivation of the potato in Europe and North America began only in the last century, it already has influenced the course of history to a notable extent. It may not be long before the study of civilization will be reckoned as a branch of biology, instead of being approached through philosophical abstractions. A higher plane of agricultural consciousness is being reached and the tendency of historical writers and ethnologists to leave agriculture out of account undoubtedly will be corrected.

The backward state of knowledge and thought in relation to the plant basis of our existence is difficult to understand, except as another striking illustration of the tendency of the human mind to reach out to distant or mysterious things and neglect what is close at hand. Hardly a century has passed since the art of systematic selection of crop plants was revived in Europe, and the possibilities of introducing new crops began to be seriously considered. Though many chance introductions had been made since the times of the Crusades and the discovery of America, the need of a thorough investigation of such possibilities of improvement of agriculture is only beginning to be appreciated.

It was well known to the Romans that superior sorts of plants as well as of animals could be developed by selection, and that deterioration follows when selection is neglected, but this knowledge was lost for centuries and is only now being recovered. The Romans had a highly developed agriculture which fell into decay when the energies of the nation were devoted to urban pursuits and to exploitation of foreign countries. Without an agricultural background, the facts of history can have little of practical significance for avoiding mistakes of the past or finding safely progressive courses for the future.

Plants Domesticated Before Animals

The traditional assumption of an original pastoral state as the first step in the development of the art of agriculture is hardly to be maintained, because the wandering life of shepherds and herdsmen is not a favorable condition for the domestication of plants. A predatory animal like the dog, with a strong instinct for running in packs and following an accustomed scent, might he adopted readily, even by the roaming savages of a pre-agricultural age, but the domestication of grazing animals is different and would be much easier for people already adapted to a settled existence. Thus the domestication of animals may be considered as a secondary problem, a consequence rather than a cause of the domestication of plants.

Figure 3
Figure 4
Amarantus candatus, one of the "pigweeds" grown as seed-crops. This plant is cultivated in the temperate valleys of southern Peru in the district of Ollantaytambo. The seeds "pop" like Indian corn, and taste much the same. (Natural size.) Two species of pig-weeds, the well-known Chenopodium quinoa and the smaller and less known C. canihua, are grown for their seeds in the table-lands of southern Peru, especially at high altitudes where the seasons are too short for Indian corn. Quinoa is raised in large quantities, mostly for brewing the native beer, though the seeds of white varieties can be boiled and eaten like oat-meal. The small species, canihua, is sown after potatoes at the upper limit of cultivation, above 14,000 feet, and is used as a travel ration by the shepherds who go out with the herds of llamas and alpacas. See Foot-Plow Agriculture in Peru, Smithsonian Report for 1918.

Figure 5
The plants grow to about four feet high and form a dense mass of seed at the top, the seed cluster of a small plant being shown in natural size in Figure 4. The heads are of several colors, red, pink, yellow, and white. Attempts have been made to introduce quinoa into the United States, but thus far without success.

On the other hand, it need not be supposed that all pastoral peoples have previously been cultivators, though some undoubtedly have been. Primitive neighbors of agricultural people may adopt domesticated animals before they adopt plants. Like the patriarchs of the Old Testament, the Navajoes of New Mexico now have large herds of sheep and cattle, but we know that these are a recent acquisition, and that such cases do not prove an original pastoral state, preceding the domestication of plants. Payne has considered that the domestication of animals would require a settled existence, though not recognizing the need of a prior domestication of plants as the basis of such a mode of life.

On account of our familiarity with the histories, traditions, languages, and ruins of the Mediterranian countries, greater antiquity of civilization in that part of the world is generally assumed, emerging from a background of pastoral life, but the domestication of plants must have begun in remotely prehistoric times. The histories of Egypt and Chaldaea are being read, and show that many plants, and animals as well, had been domesticated and used for centuries and milleniums before the days of Abraham. The problem of domestication should be approached with as little of historical bias as possible, if the biological indications are to be appreciated.

Figure 6
The coca shrub, which furnishes cocaine, is cultivated and used extensively in Peru. Though tobacco was known to the ancient Peruvians it was considered injurious, while the chewing of coca leaves was a universal habit of the male Indians. Coca is a handsome plant, with white, scarlet berries and rather delicate pea-green leaves.

Our historical prejudice is so great as to make it very difficult to consider such a possibility as that of civilization having originated outside of the traditional area of the Mediterranean countries and Western Asia. It has required 400 years since the discovery of America for us Europeans to begin to realize that there was a really indigenous development of civilization in America. It is still very difficult for many intelligent people and even for scientific investigators to see that the origin and development of agriculture in America is to be recognized as a fact that stands on its own separate foundation of evidence, quite apart from any traditions regarding the development of civilization in the Eastern Hemisphere, our so-called "Old World."

Agriculture Indigenous in America

That the agriculture of the native peoples of North and South America was not introduced from the Old World but had an independent, indigenous development, is demonstrated by the fact that the American agriculture was based on native American plants. The assumption of Old-World origin of the primitive civilizations of America has been debated for 400 years, from the days of Columbus to the present time, without reaching a definite conclusion from historical, ethnological or linguistic data, but the evidence of the plants is unequivocal, and no other evidence appears so definite and conclusive, from a biological standpoint.

*MARTIUS, C. F. P. VON, 1867. Ethnographie und Sprachehenkunde Amerikas.
PAYNE, F. J., 1892. History of the New World Called America.

Biologists are familiar with the fact that the different families, genera and species of plants and animals have definite geographic distributions, but historians or other writers who do not have a biological outlook may leave out of account some of the most significant factors in locating the centers of primitive culture. The essential relation of the cultivated plants to the development of civilization in America was stated long ago by Martius and has been recognized by Payne and other more recent writers, though still commonly overlooked.*

From the present-day knowledge of the cultivated plants it appears that the traditional ancient world of our civilization, in the Mediterranean countries, was not the scene of an indigenous growth of agriculture and the attendant arts. Each of the important crops, as well as the industrial products of the ancient Romans, Greeks and Phoenicians, when traced back, is found to have been exotic. The linguistic and archaeological indications are in line with the ancient traditions of successive introductions of grapevines, fruit trees and cereal crops. In the Old World the search for the origin of civilization has led to no definite indication of the place or the conditions where domestication was first accomplished and the early stages of agricultural development were passed.

Some of the historians recognize that the natural conditions of Egypt and Mesopotamia were those of swampy forested flood plains, which needed to be reclaimed by people already accustomed to the practice of irrigation and other specialized methods of agriculture. Such alluvial valleys are fertile and can be made permanently productive, but the natural flood-plain conditions were not favorable for the domestication of cereals, nor even for the existence of most of the crop plants in a wild state.

*See Trans-Pacific Agriculture, Science N. S., Vol. XLVI. No. 1192, page 435, November 2, 1917.

Archaeologists now concede that the first civilizations of Egypt and Assyria were not indigenous, but were brought by a foreign race supposed to have come into both countries from southern Arabia. The art of agriculture already had reached a highly developed state when it was introduced into Egypt and Assyria. A prehistoric civilization existed in southern Arabia, as shown by remains of agricultural terraces and massive stone-work, but there the trail ends, unless eastern origins are sought. That the island of Madagascar was occupied, as well as the East Indian and Pacific islands, by a prehistoric seafaring people with a highly developed system of agriculture, is a fact that may have significance in the general history of agriculture. Linguistic similarities have been claimed by philologists between the Oceanic languages and the ancient Semitic and Aryan tongues. Of course, the traditional assumption has been that any prehistoric influences must have extended from Egypt or Assyria, from India or China, to the Pacific islands or to the American continent. The possibility of a prior development of agriculture and primitive civilization in America has received little consideration.*

In Peru, on the other hand, there is no such difficulty in visualizing a primitive state of agriculture, which still exists among the native people of the narrow, pent-in valleys of the eastern slopes of the Andes. No other conditions appear so well calculated for forcing a primitive people to domesticate and propagate plants as these gorge-like valleys, commonly a mile deep and rimmed above with perpendicular cliffs or with perpetual snow. The primitive people who took refuge in these valleys were under the greatest imaginable pressure to make use of every local means of subsistence, since they were precluded from the usual recourse of savages who wander about in search of food.

In the modern Quichuas, as the native agricultural people of the higher Peruvian valleys are called, we may see the representatives of an ancient people still surviving under conditions where agriculture certainly was not borrowed or introduced from abroad, but appears to have been strictly indigenous. That the native farmers of Quichua-land are a very simple and rude people does not render them less interesting, but leaves them the nearer to the primitive conditions of existence that supported and made possible the higher development of the native culture of the Inca and pre-Inca periods.

The same conditions of isolation and restriction to small communities, that may have forced the ancient people to domesticate plants and become agricultural, still tend to keep people in the same places and hold them to a very primitive existence, notwithstanding the lapse of time, which may be very great. Though the Inca empire, overturned by Pizarro, probably had not been established for many centuries, several earlier epochs of pre-Inca civilization are now recognized by archaeologists, on the basis of different types of megalithic stonework. Indeed, the most massive and finely fitted stonework is now ascribed to the pre-Inca ages.

Relative Antiquity of Domestication

Biology shows that the system of agriculture was indigenous in America, since American plants were used, and also affords indications of the great antiquity of agriculture in America. Such evidence comes from comparing the cultivated species of plants with their nearest wild relatives. Such comparisons in America show many cases of wide divergence, so wide, in fact, that it has not been possible to identify with certainty the wild type of several of the most important species, as corn, tobacco, beans, peanuts, potatoes, and tomatoes. In this there is a striking contrast with the results of similar studies of the cultivated plants of the Old World, where most of the cultivated species have wild prototypes that are very easily recognized. The much closer resemblances between the domesticated and the wild forms in the Old World suggest that domestication has taken place more recently. Thus the biological factors indicate a greater antiquity of agriculture in America.

Figure 7
Figure 8
Fruits and seeds of the cassava plant (Manihot), a very important and widely distributed tropical root-crop. Since most of the varieties are seedless like other plants grown for long periods from cuttings, the finding of this seed-bearing variety, both spontaneous and cultivated, may indicate the persistence of a wild type in the eastern valleys of Peru. A handsome blue-flowered lupine called "tarhui," probably Lupinus cunninghamii, is cultivated in the temperate valleys around Ollantaytambo. The seeds are eaten, but require special preparation which includes soaking in water for eight days to remove a poisonous principle.
Figure 9
A ruined terrace below the "citadel" at Ollantaytambo with the retaining wall partly fallen, exposing at the right the two layers, showing the artificial placement of the soil when the terrace was constructed. The upper layer of fine soil is from two to three feet thick, and under it is a deeper layer of coarse rubble. The right-hand part of this illustration is from the National Geographic Magazine.

Unity of American Agriculture

Among the historians and ethnographers various opinions have been held regarding priority of civilization, as between Mexico and Peru. Probably the weight of opinion has inclined toward Mexico, because there a more advanced stage of civilization is supposed to have been reached. The exuberant development of architecture in the ancient Maya cities, the elaborate calendrical system, and the close approach to an art of writing, are features that have attracted much attention to the Mexican region.

Of Peru it may be said that the art of agriculture was more highly developed, the social system more advanced, and religion less barbarous. As an alternative of the graphic art, the Peruvians developed and used extensively a method of making numerical records with knotted cords, known as quipus. An elaborate calendrical system was not needed in Peru because the seasons were determined by a method of direct observation.

More important than to appraise the special attainments of Mexico and Peru is to recognize the underlying fact that in both countries agriculture was based on the same plants, so that the prehistoric agriculture of America may be considered as a single system, developed from a primary center of domestication. In Mexico, as in Peru, the chief food product was Indian corn, or maize, and many other plants of the lower Peruvian valleys were cultivated throughout tropical America, including Mexico, as sweet potatoes, cassava, xanthosoma, gourds, squashes, peppers, beans, peanuts, tobacco and cotton. That the same series of crop plants should attain such a wide distribution shows that many migrations took place and that many contacts were established. Food habits are very persistent and not readily changed. Wherever it is possible to do so, people will carry with them the food-plants to which they are accustomed, instead of domesticating new plants or adopting new foods.

Location of Maya Civilization

How the prehistoric contacts or communications were made between Peru and Mexico is a question that ethnologists may determine. The specialized worship of maize gods among the ancient Mexicans, and the many traditions of the coming of maize among the more northern tribes, are indications of an imported culture. Two lines of communication from Peru to Mexico are suggested by facts already known. Archaeologists now recognize in Central America the remains of pre-Maya cultures which may connect with South America by way of the Pacific coast or the Isthmus of Panama, while the distinctive Maya culture may have entered by way of the Caribbean Sea or the West Indies. The pre-Maya period is characterized, for example, by hollow-legged pottery, while the Maya pottery and stonework show elaborate headdresses, facial mutilations and tongue-boring that suggest Carib relations. The Mexican culture-deity, Quetzalcoatl, is alleged to have come from the East. Carib and Arawack tribes like those of the West Indies are widely scattered in South America, across the entire Amazon basin, from the Andes to the Guianas. The ancient seats of the Maya culture have been located through Morley's researches. The earliest dated monuments are in the lowland forests of the Peten district of Guatemala, not in the salubrious tablelands or the Pacific coast districts where historians and geographers have assumed that the Mexican civilization must have developed.

If any weight is to be given to the reasoning that many writers have followed regarding effects of environment, an indigenous development of the Maya culture in the eastern lowlands must appear improbable. In the light of present knowledge of Maya-land, it is interesting to review the argument of Squier, the chief historian of Central America published in 1858:

The geographical and topographical features of all countries have had, and always must have, an important and often a controlling influence upon the character and destiny of their populations. The nature and extent of this influence receives a striking illustration both in the past and the present condition of Central America. At the period of the discovery, it was found in the occupation of two families of men, presenting in respect to each other the strongest points of contrast. Upon the high plateaus of the interior of the country, and upon the Pacific declivity of the continent, where the rains are comparatively light, the country open, and the climate relatively cool and salubrious, were found great and populous communities, far advanced in civilization, and maintaining a systematized religious and civil organization. Upon the Atlantic declivity, on the other hand, among dense forests, nourished by constant rains into rank vigor, on low coasts, where marshes and lagoons, sweltering under a fierce sun, generated deadly miasmatic damps, were found savage tribes of men, without fixed abodes, living upon the natural fruits of the earth, and the precarious supplies of fishing and the chase, without religion, and with scarcely a semblance of social or political establishments.

It is impossible to resist the conviction that the contrasting conditions of these two great families were principally due to the equally contrasting physical conditions of their respective countries. With the primitive dwellers on the Atlantic declivity of Central America, no considerable advance, beyond the rudest habits of life, was possible . . . .

Civilization could never have been developed under such adverse conditions. It can only originate where favorable physical circumstances afford to man some relief from the pressure of immediate and ever-recurring wants—where a genial climate, and an easily-cultivated soil, bountiful in indigenous fruits, enables him not only to make his permanent abode, but to devote a portion of his time to the improvement of his superior nature.

Such arguments appear logical and are still being elaborated by geographers, but often prove too much, as in the present case. The Maya civilization did exist and was maintained for centuries under the tropical low-land conditions that appear so adverse. The ancient low-land civilization gave rise to the table-land civilizations, and also was more advanced, or at least more specialized. As so often happens, the logical and the biological reckonings do not coincide. The biological factors dominated the environmental factors. Human ability and organization achieved the "impossible" in the prehistoric ages, as they do to-day. Our own civilization has still to understand and appreciate, if not actually to imitate, some of the achievements of the primitive and prehistoric peoples.

(Concluded in the March Number)